The present disclosure relates to image forming apparatuses having a function to control a toner remaining amount for image formation and toner remaining amount control methods.
In recent years, an image forming apparatus capable of performing color printing has become more general. The image forming apparatus, for example, is a copier or a multifunction peripheral. This type of image forming apparatus realizes color printing by combining a plurality of recording agents. For example, the plurality of recording agents are toner having four colors: cyan (C), magenta (M), yellow (Y), and black (K). Many image forming apparatuses control the remaining amount of each recording agent. In addition, the image forming apparatus has a function to inform a user of a near-empty state. The near-empty state is a state in which the recording agent is running out and image formation will be impossible soon. A user directly operating the image forming apparatus is informed of the state by screen display, buzzer, and so on. In addition, in some cases, an administrator of the apparatus or the like that is not directly operating the image forming apparatus is notified by e-mail transmission to a specific destination that is previously designated and so on.
In controlling the remaining amount of recording agent as above, a dot-count method is often used for calculating the amount of recording agent consumption. The dot-count method is to count the number of dots printed on a transfer target such as paper, based on the image data entered into the image forming apparatus as a printing target. Then, the amount of recording agent consumption is calculated by multiplying the count value by the amount of the recording agent consumed for printing one dot. It should be noted that for an image forming apparatus that performs multi-tone printing (for example, 256 tones), a print having tones over a previously designated threshold, for example, is counted as dots.
In controlling the remaining amount of recording agent as described above, it is required to grasp the remaining amount of recording agent accurately so as to prevent a decrease in productivity of the image forming apparatus as well as allowing appropriate supply (replacement) of the recording agent. However, according to the dot-count method as described above, even multi-tone printing is binarized and counted. Therefore, this results in a state where the recording agent is used for printing that is not counted as dots, or a state where only a small amount of recording agent is consumed for the printing counted as dots, compared to the amount of the recording agent consumed for printing one dot as described above.
To prevent this, an image forming apparatus performs life management (toner remaining amount control) of a toner cartridge, based on the dot count and the drive time of a developing roller included in a developing device. The developing device forms a toner image by attaching toner to an electronic latent image formed on a photosensitive drum. In addition, an image forming apparatus counts the number of dots by classifying the dots, according to the printing pattern, into groups such as the dots not less than a threshold, four consecutive dots, and isolated dots, and calculates the amount of toner consumption based on these count values.